Mount Prospect, Illinois 7 Day Weather Forecast

Wx Forecast - Wx Discussion - Wx Aviation

102
FXUS63 KLOT 281726
AFDLOT

Area Forecast Discussion
National Weather Service Chicago/Romeoville, IL
1226 PM CDT Tue Apr 28 2026

.KEY MESSAGES...

- A cooler and drier pattern starts today and will last into
  early May.

- There is a threat for frost Friday night across the region.

&&

.DISCUSSION...
Issued at 109 AM CDT Tue Apr 28 2026

Early this morning, a 994 mb surface low was located over the
Upper Peninsula of Michigan with a cold front stretching
southward through the Great Lakes and into the lower Mississippi
River Valley. Expansive low-level stratus is present in the
wake of the cold front, stretching from northern Wisconsin
through northern Missouri. The departing low pressure system is
just one piece on the board this morning with aggregate
troughing across the northern United States, with several
embedded shortwave-length troughs propagating within. The
overarching pattern is setting the stage for the well-
advertised pattern change toward predominantly cooler and drier
conditions across much of the northern United States.

Today will be noticeably chillier than yesterday. A robust push
of low-level cold air advection (driven by northwesterly winds
gusting 30 to 35 mph overnight) will drive temperatures down to
the upper 40s to lower 50s by daybreak. With low stratus
expected to be prevalent across the region through the morning,
temperatures will be slow to warm with most areas remaining in
the 50s through early afternoon. Areas that experience clearing
this afternoon will have the best opportunity to jump into the
lower 60s, with current indications favoring locals north of
I-80 and west of the Fox Valley. Northwesterly winds should
gradually ease throughout the day.

Tonight, an upper-level shortwave embedded in the broad
troughing aloft will propagate through the Ohio River Valley.
Occasional flares of frontogenesis acting upon the cyclonically-
curved baroclinic zone across the Lower Great Lakes will
support scattered showers through the overnight hours.
REsidually dry low-level air may act to limit the overall
duration and footprint of showers tonight, with overall rainfall
amounts favoring less than one quarter inch at any given
location. Overnight lows will fall to the 40s.

Tomorrow morning, the upper-level shortwave will move away from
our area. With a camp of model guidance advertising broad low-
level convergence along the Lake Michigan shoreline (almost an
inverted low-level trough-like structure), showers may overstay
their welcome across northeastern Illinois and northwestern
Indiana through early afternoon. Decreasing cloud cover through
the afternoon should allow an opportunity for highs to warm
toward 60 degrees with cooler conditions near Lake Michigan due
to onshore flow. Tomorrow night looks relatively cool as surface
ridging and clearing skies sets the stage for overnight lows in
the upper 30s to lower 40s.

Toward the end of the week and beyond, the pattern will be more
or less the same with aggregate upper-level troughing and the
occasional passage of shortwaves to support a few showers. The
coolest day of the pattern looks to be Friday in the wake of an
upper-level shortwave anchored to a pool of cooler 850mb
temperatures, leading to highs in the low to mid 50s (if not a
smidge colder). Friday night hence looks to be a standout for
frost potential as a surface high moves into the region allowing
for calm winds and overnight temperatures in the low to mid
30s. At least some moderation in temperatures may occur by the
weekend as the aggregate upper-level troughing drifts eastward.

Borchardt

&&

.AVIATION /18Z TAFS THROUGH 00Z THURSDAY/...
Issued at 1226 PM CDT Tue Apr 28 2026

Key Aviation Messages for the current TAF period:

- Scattered low/no impact showers overnight. Possibly again on
  Wednesday

There is some lingering high MVFR cigs over northeast Illinois
and northwest Indiana this afternoon; however, they are slowly
eroding away. Perhaps they linger just a little longer than in
the TAF, but with many obs already reporting VFR conditions
giving confidence in a VFR forecast this afternoon. Winds remain
out of the west, though occasionally flirting with a southwest
direction, and around 10 knots with occasional gusts to 20
knots early this afternoon.

Wind direction trends are a little challenging through the
overnight as weak surface troughs pass over the area. Winds are
expected to be less than 10 knots, but there is lower
confidence in specific wind directions overnight. Models
continue to suggest rain showers overnight. But with weak
forcing probability of showers at any one specific terminal is
too low for TEMPO/prevailing mention presently. The better
forcing is to the south, so perhaps areas closer to KGYY have
the best chance, but for now maintained VCSH as showers are
possible.

Northeast winds are expected to start the day tomorrow with a
chance they flip over to west of north in the afternoon. As
another wave of moisture pushes in overhead and increases cloud
cover, there is another chance for a shower to pop-up
(especially near the lake), but confidence was too low to add
into the TAF. While thunder is not expected with any of the rain
chances, if a shower does develop there could be a brief window
of high MVFR cigs with the rain.

DK

&&

.LOT WATCHES/WARNINGS/ADVISORIES...
IL...None.
IN...None.
LM...None.

&&

$$

Visit us at weather.gov/chicago